Struggling at events of ode function

Hello,

I'm trying to use events function to find the coordinates of a ODE function of n variables. What I want is to find the results of x(i)=certain value m times.

I've read the help about events but I don't get how to implement it. I've also seen other posts and the ball bounce example but what I want to know is how to tell the program that the event is x(2)=0. At the moment I have:

[value,isterminal,direction] = events(t,y);

    incT=[t0,t0+step];
    i=0;
    resu=zeros(talls,length(condIni)+1);
    while i<talls
        [T,Y,TPS,YPS,~] = ode45( fun,tspan,condIni,options );
        if isempty(TPS)~=1
            i=i+1;
            incT=[T(end) T(end)+step];
            condIni=YPS;

            resu(i,1)=TPS;
            resu(i,2:end)=YPS;
        end
    end

This is part of my code, apparently not defined variables as 'talls' or 'step' are defined previously.

Thanks